1. FIELD OF THE INVENTION
The present invention relates to an apparatus including a rotating chamber for separating a denser material from a less dense material. Either a solid is removed from a slurry or a liquid is separated from a mixture of liquids of different densities.
2. DESCRIPTION OF THE PRIOR ART
Centrifugal separation of respective solid and liquid constituents is well known in the prior art. In a first type of separator, the solids are trapped in a rotating drum, and the liquid fraction permeates therethrough, escaping to the outside of the drum. The drum is generally perforated to accomplish the selective entrapping of solids. This approach is seen in U.S. Pat. No. 2,312,829, issued to Byron M. Bird et al. on Mar. 2, 1943.
Some centrifugal separators cause the solid to migrate along the walls of the drum in response to centrifugal force. U.S. Pat. No. 4,846,781, issued to Benjamin V. Knelson on Jul. 11, 1989; U.S. Pat. No. 4,983,156, issued to Benjamin Knelson on Jan. 8, 1991; and U.S. Pat. No. 5,156,751, issued to Neal J. Miller on Oct. 20, 1992, are exemplary. Solids are trapped in grooves formed in the drum for this purpose in the inventions of Knelson. Solids are discharged centrifugally in Miller's device.
The above cited prior art references share the characteristic wherein the chamber defined by the rotating drum is of fixed dimensions. Variable dimension chambers are also possible. Norwegian Pat. No. 95,639, dated May, 1960, and German Pat. No. 239,405, dated October, 1911 both disclose chambers which expand axially under the influence of centrifugal force. This expansion is resisted by a spring in the Norwegian reference.
The German device is directed more towards dispensing sugar in an even stream than in accomplishing separation.
The Norwegian invention is explicitly intended for separation, and provides two mating bowls which define a centrifugal separating chamber therebetween. These bowls spread apart radially under centrifugal action, and solids are discharged through the variable width gap established between the bowls.
Although there are certain shared features between the Norwegian invention and the present invention, there are also significant differences. The Norwegian invention lacks a baffle provided in the present invention, and has perforated bowls for enabling escape of liquids. Resultant circuits of liquids through the two devices is markedly different. Also, the Norwegian separator is potentially susceptible to blockage by particles larger than the perforations in the bowl walls. By contrast, in the present invention, there is only one escape orifice for solids. This orifice is larger than the perforations found in the Norwegian device. Also, this orifice becomes progressively larger with increasing rotational speed.
None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed.